fiftee3 - Your casting# "3837004" matches up with a 1955-57 235 with the large (low position) water pump hole casting. The casting date code "I 6 6" decodes as:
I = September 6 = 6th day of September 6 = 1956
The stamped serial# "F920H" decodes as: F = Flint plant 920 = September 20th H = 3100/3200/3600/3800 Regular Production 235 for 1957 model year (taken from the
GM Heritage Center 1957 Chevrolet Truck Data PDF.
The "3836848" head is most likely the correct 235 head for your engine. The numbers on the distributor side of the head are just basic casting codes for the foundry. To better determine the age of your head, look for a casting date code similar to the one on the side of the block, but under the valve cover and just inside the drives side valve cover gasket flange.
Are you looking to list your engine for sale in the
Truck Parts For Sale forum???